Coiled tubing well tool and method of assembly

ABSTRACT

A long, well tool which effectively performs as an integral part of a typical coiled tubing string and accordingly can be ran continuously into a pressurized wellbore with the same deployment equipment as used with known coiled tubing. The tool is comprised of a plurality of elements (e.g. perforating charges or logging sensors such as hydrophones, geophones, gamma ray sensors, gravity sensors, etc.) fixed at spaced, known distances from each other within a flexible housing, e.g. a length of coiled tubing.

1. TECHNICAL FIELD

The present invention relates to a downhole well tool which iseffectively incorporated into the lower end of a string of coiled tubingand in one of its aspects relates to running a long well tool having aplurality of elements (e.g. logging sensors, perforating charges, etc.)into a pressurized wellbore without the need of specialized, pressuredeployment equipment or procedures.

2. BACKGROUND OF THE INVENTION

It has long been routine to run a long well tool into a wellbore tocarry out a particular operation. For example, it is routine to “log” awell after or during drilling to determine various characteristics ofthe subterranean formations traversed by the wellbore. That is, a wellmay be logged to determine the presence and location of any oil/gasdeposits that may lie adjacent the wellbore. Some of these loggingoperations require taking measurements at several spaced points withinthe wellbore and then collating the collected data to produce thedesired log.

Typically, in the past a particular type of sensor (e.g. geophone,hydrophone, gamma ray sensor, gravity meter, etc.) was lowered on awireline or string of tubing to a first point in the wellbore and ameasurement was taken. The sensor was then raised or lowered to a secondpoint where a second measurement was taken and so on until the desirednumber of measurements was made. Not only is this operation timeconsuming, it can also lead to inaccuracies in the final log since, inmany instances, it is critical not only to know the depth at which eachmeasurement is taken but also the exact distances between the respectivemeasurement points.

More recently, logging tools have been proposed wherein a plurality ofsensors are fixed at known spaced intervals within a defined housing.Not only does this allow multiple measurements to be taken with a singlepositioning of the tool but it also maintains an exact, known distancebetween the fixed sensors at each measurement point. For example, seethe tool disclosed in U.S. Pat. No. 6,671,057 B2 wherein a plurality ofgravity sensors are spaced within a housing which, in turn, is loweredinto a wellbore on the end of an armored electrical cable, drill pipe,or coiled tubing string. However, since the sensors are fixed in a rigidcylindrical housing (e.g. length of pipe, casing, or the like), thenumber of sensors that can be mounted in the rigid housing is limitedsince the overall length of the tool (i.e. housing) has to be keptrelatively short in order to transverse deviated and horizontalwellbores typically encountered during the logging operation.

Also, there are problems in deploying “long” tools into pressurizedwells; i.e. going from atmospheric pressure to the substantial higherpressures in the wellbore. This is true for not only logging tools butfor other types of long well tools, e.g. casing perforating tools havinga plurality of explosive charges spaced within a housing. Normally, along length of pipe, riser, or “lubricator” is supported on the valvedwellhead or “tree”. A typical lubricator has a pack-off, grease seal, orother annular sealing element that allows well pressure to be containedinside the lubricator. With known “shorter” logging tools, the entirelength of the rigid housing which is attached to the end of a wireline,pipe, or coiled tubing string is positioned within the lubricator withthe tree valves closed to block the well pressure. The lubricator isthen pressured to well pressure and the tree valves into the well areopened. The annular sealing element on top of the lubricator holds aseal between the well pressure and the atmosphere and allows thewireline or coiled tubing to lower the tool into the pressurizedwellbore.

Problems arise when deploying long tools which will not fit within thelubricator. Presently, this is done by making the tools in shortercomponents and sequentially lowering each respective component a shortdistance down the wellbore. As will be understood by those skilled inthis art, slips and rams of a blow-out preventer (BOP), which has beeninstalled on the tree, are closed on the component being lowered. Thepressure in the lubricator is bled down above the sealing rams and thelubricator is lifted off the BOP while back stripping the lowering means(e.g. wireline, coiled tubing, etc.).

The lowering means is then disconnected from the tool component beingheld by the rams and the next component is attached thereto. The nextcomponent is then positioned in the lubricator which, in turn, is swungback over the wellhead and the next component is mated with the previouscomponent held by the rams. The next component is mated up to theprevious component and the lubricator is pressure tested to at leastwellbore pressure. The rams are then opened and the assembled componentsare lowered some distance into the wellbore before the process isrepeated as many times as necessary to deploy the respective long tool.

This deployment procedure is both a time intensive and tedious job withrisks associated with the rams not holding the well pressure, the slipsnot keeping the tool from being ejected from the wellbore, etc. Eachstep must have pressure containment to keep from flooding the toolduring pressure deployment, or from wellbore fluids flowing up throughthe components while they are in the rams. Unfortunately, logging toolsusing geophones, hydrophones, or multi-component gravity sensors aretypically “long” tools requiring many repetitions of the above describeddeployment steps.

Accordingly, a need exists for a long well tool having a relativelylarge number of elements (e.g. logging sensors, perforated charges,etc.) mounted therein in a fixed, spaced relationship (i.e. known exactdistance between elements) which can be used in vertical, deviated,slanted and/or horizontal wellbores and at the same time be capable ofbeing easily run into and out of a pressurized wellbore in a continuousoperation.

SUMMARY OF THE INVENTION

The present invention provides a long well tool (e.g. logging tool,perforating tool, etc.) which can be ran into a pressurized wellborewithout requiring the time consuming and tedious operating stepstypically required in such operations. Basically, the tool is one whichperforms as an integral part of a typical coiled tubing string andaccordingly can be ran continuously into a pressurized wellbore bymerely using the same deployment equipment as that used in running astandard coiled tubing string into a well. The housing of the tool isrelatively flexible as is the mounting of the elements (e.g. loggingsensors) within the housing so the tool, itself, can easily be coiledonto and off of a typical reel of known coiled tubing systems.

More specifically, a plurality of elements (e.g. shaped charges orlogging sensors such as hydrophones, geophones, gamma ray sensors,gravity sensors, etc.) are spaced at known distances and are coupledtogether with a spacer (e.g. individual, known lengths of prima cord,cable, or a hollow rod or the like) to form an array of spaced elements.In the logging tool, the sensors are coupled together withpower/transmission wire(s), preferably through the hollow spacers, andthe fixed array of sensors is positioned within the flexible housing.This housing may be any material which is durable enough for thispurpose while at the same time is compatible with coiled tubing spoolingtechnology; e.g. a length of the coiled tubing, itself.

The actual position within the housing of each element is determinedfrom the outside of the housing and each element (e.g. sensor) is thensecured to the housing at that position by any appropriate means, e.g.dimpling the housing at each element location. The housing, if notalready a part of the lower end of the coiled tubing string, is attachedto the coiled tubing string and effectively becomes an “integral” partof the “spoolable” string.

By effectively incorporating the plurality of elements into the coiledtubing, itself, long tools (e.g. 500 feet or more) can easily andquickly be run into a pressurized well using only the same deploymentequipment and techniques used in running any typical coiled tubingstring into a well. This eliminates the several tedious steps previouslyrequired with the running of long well tools where the tools had to bemade up by joining components as the tool is being lowered through thewellhead.

BRIEF DESCRIPTION OF THE DRAWINGS

The actual construction operation, and apparent advantages of thepresent invention will be better understood by referring to thedrawings, not necessarily to scale, in which like numerals identify likeparts and in which:

FIG. 1 is a perspective illustration of a typical coiled tubing surfaceunit and an enlarged, sectional view of the lower end of a wellborehaving the well tool of the present invention positioned therein; and

FIG. 2 is a further enlarged sectional view of a portion of the presentwell tool taken within lines 2-2 of FIG. 1.

While the invention will be described in connection with its preferredembodiments, it will be understood that this invention is not limitedthereto. On the contrary, the invention is intended to cover allalternatives, modifications, and equivalents that may be included withinthe spirit and scope of the invention, as defined by the appendedclaims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, FIG. 1 illustrates a well 10 having awellbore 11 and a wellhead 12. As will be understood, wellbore 11 can becased (as shown), lined, open, or otherwise completed and can bevertical, slanted, and/or horizontal. A typical, coiled tubing system 13is positioned on the surface for running a coiled tubing string 14 intoand out of the wellbore 11 through wellhead 12. As will be understood inthe art, the term “coiled tubing”, as used herein is a continuous lengthof a relatively small diameter (up to 6 inches), thin-walled relativelyflexible metal tubing (e.g. steel or other high-strength alloy tubingsuch as titanium alloy, chrome alloy, or composite material) 14 whichcan be wound or coiled onto reel or spool 15 which, in turn, can bemounted on a mobile trailer 15 a or the like.

Reel 15 may include a “level wind” mechanism 16 or the like to align thecontinuous length of tubing in relatively uniform layers as the tubingis reeled onto/off reel 15. The tubing is moved into/out of wellbore 11by injection unit 17, which uses a pair of endless chains 19 to grip thetubing. Being continuous, no joints of pipe have to be made-up orbroken-out as the tubing 14 is run into/out of the well. Coiled tubingunits such as that described are well known and are commerciallyavailable in the industry.

In accordance with the present invention, a long element or plurality ofelements 21 are fixedly positioned within a relative flexible length oftubing or the like which, in turn, forms a pressure housing 22 for thepresent well tool 20. Housing 22 can be formed from a length of commoncoiled tubing which, in turn, is typically formed of steel, corrosionresistant alloy, titanium, fiberglass, composite materials or othersuitable material compatible with coiled tubing spooling technology. Thehousing 22 may be slightly more rigid than the coiled tubing used onreel 15 if it is still within the standard back tension capacity of thereel required to bend the tubing string as it is coiled onto the reel.Preferably, pressure housing 22 is substantially the same nominaldiameter as that of the coiled tubing 14 but, it should be recognizedthat it may be slightly larger or smaller when used with knownexternally upset coiled equipment and techniques.

Also it is known that that there is little difference between standard80 ksi (i.e. 1000 psi) jointed pipe and 80 ksi coiled tubing. The twotubulars are extremely similar in forces required to bend them, loadcapacity, and in almost every other ‘macro scale’ test results. The onlyknown real difference between the two is their respective crystalstructures which allows standard coiled tubing to bend more timeswithout breaking. Precise control of the alloying materials (e.g.nickel) in the respective tubulars help maximize the amount of bendingbefore breaking.

Elements 21, as illustrated in the Figures, are intended to be merelyrepresentative of known explosive charges or, in logging tools, may beany of the different, known sensors routinely used in every day loggingoperations and are not intended to illustrate the details of any oneparticular type of sensor. In perforating tools, elements 21 representshaped, explosive charges such as used in known perforating tools andare connected by lengths of prima cord 26 or the like. When well tool 20is a perforating tool, it is preferably connected to the lower end ofcoiled tubing string 14 by any type of known disconnect coupling 14 a(FIG. 1), e.g. manual overpull, pressure or electrically actuated, etc.,so the well tool can be left in the hole. Also, a disconnect coupling,such as 14 a, can be used where tool 20 is a logging tool so that thetool can be released if it should become stuck in the hole. Further,though not shown but well understood in the art, coiled string 14 mayinclude check valves, vents, etc. to control flow into or out of thestring during lowering and/or raising the tool.

Where elements 21 are comprised of logging sensors, they may be selectedfrom any known type of sensors, e.g. hydrophones, geophones, gravitymeasuring devices, gamma ray sensors, or any other commonly used loggingsensors where a plurality of the respective measurements are to be madeat fixed distances from each other in a single operation. That is, apredetermined number of hydrophones 21 may be fixed at known, spacedintervals within a flexible housing 22 to thereby form a hydrophonelogging tool 20 in accordance with the present invention while, inanother instance, a number of gamma ray sensors 21 may be fixed in aknown spaced relationship within a flexible housing 22 to form a gammaray logging tool in accordance with the present invention, and so on.

While various techniques may be used to position and fix the pluralityof selected elements 21 in a spaced relationship within a flexiblehousing 22 without departing from the present invention, the followingdescribes what is considered as being the easiest known technique fordoing this. A length of coiled tubing which is to form flexible housing22 is reeled out and laid onto the ground. Since the tool 20 will beflexible and reelable onto and off of reel 15, tool 20 (i.e. flexiblehousing 22) can practically be of any length (e.g. 500 feet or more andcan contain 10 elements 21 (e.g. sensors) or more when spaced at adistance of 50 feet from each other). However, it should be realizedthat flexible housing 22 may be comprised of the entire length of coiledtubing 14 on reel 15 thereby allowing substantially any length ofelement spacing.

In logging tool 20, a plurality of the desired sensors, e.g.hydrophones, are first coupled together in a spaced relationship byrespective, known lengths of a substantially rigid but relativelyflexible spacer means (e.g. spacer members 25). Preferably, spacermembers 25 are formed of known lengths of a hollow rod or tubing or thelike which are coupled between two adjacent sensors 21. Since thediameter of rod 25 is much smaller than that of flexible housing 22,bending of tool 20 will have very little detrimental effect on theconnecting rods, themselves. Once assembled and electronically connected(e.g. wire 26, fiber-optics, etc. within rod 25, see FIG. 2), theassembly of sensors are slid into housing 22. This allows the sensors tobe easily removed and serviced and/or replaced if and when needed andthe housing to be replaced if it should wear out. It should also benoted that communication from and between sensors may also be byelectromagnetic wave propagation powered by batteries (not shown), byvibrational energy through tool components, or by fluid pressure pulsesin the coiled tubing string.

Elements 21 may also be installed within the housing 22 by first hangingoff the entire reel of coiled tubing into a well and the lowering thestring of elements into the coiled tubing. The coiled tubing andelements are then reeled back onto the reel as a unit and then can beused for the respective intended logging or perforating operation.Further, it is possible that the elements may be pumped into a spooledreel of coiled tubing using available pumping techniques, e.g. “pressurecapstan drive”. In these instances, the lengths of rod 25 may not benecessary wherein a wireline of wrapped fiber-optic cable (not shown)will be used for support and communication back to the surface.

Once the elements are spaced within the housing, their exact location isdetermined and marked on the outside of the housing. The locations ofthe elements inside housing 22 can be determined by running a commonmetal detector along its length or can be determined more precisely byplacing a small radioactive pip tabs (i.e. very low energy gamma raysources) on each element and then locating the pip with a Geiger tube orcrystal gamma ray detector from outside the housing. A dimpling tool ofa type well known in this art, is then either slid over the housing 22or if constructed in two halves, is bolted around the housingsequentially at each element location.

As known in the art, this type of commercially-available tool has one ormore round nosed bolts which are either threaded or slidable withinopenings in the wall of the tool. The bolts are then manually threadedinwardly or are forced inwardly by cooperating hydraulic pistons toeffect indentations or “dimples” 27 (FIG. 2) in the wall of housing 22on either side of each element to thereby hold the respective elementsagainst longitudinal movement within the housing 22. The exact locationof the dimples does not have to be precise as long as the exactdistances between the adjacent dimples are known. Elements 21 can alsobe anchored at their respective locations within housing 22 by sending asignal through wireline 30 or by pressuring up the coiled tubing totrigger individual anchors (not shown) built into each element 21.

Next the uppermost element 21 a (FIG. 1) is coupled to a wireline 30(i.e. power and/or signal transmission line) which passes down throughthe coiled tubing 14. As known in the art, there are several ways todeploy wireline 30 into coiled tubing 14 while the tubing is on reel 15.For example, as will be understood in the art, a slickline (not shown)can be pumped through the entire length of the coiled tubing by using aswab cup or the like attached to the end thereof. The slickline is thenattached to end of the wireline 30 which is then pulled back through thecoiled tubing by the slickline. This pulling operation can be assistedby pumping the wireline back through the coiled tubing, if necessary.More recent methods for installing the wireline or fiber-optic cableinto a coiled tubing string is to use flow tubes (e.g. “Grease InjectionHead”) to allow the wire to be pumped into the coiled tubing with theflow tubes controlling the pressure similar to a labyrinth seal. Also, aknown pressurized “capstan drive” unit can be used to pull the wire intothe pressurized system and then driving it into the flow being pumpedthrough the reel of coiled tubing.

Once the tool 20 is assembled and connected to the wireline orcommunication cable 30, and if a separate component, flexible housing 22is connected to the lower end of coiled tubing string 14 by any numberof techniques, e.g. disconnect coupling 14 a, spoolable connectors,dimpled connectors, roll-on connectors, or weld-on connectors, noneshown but all of which are known and commercially-available, and tool 20effectively becomes an “integral” part of the spoolable coiled tubingstring. Of course, as stated throughout, housing 22 may actually be anintegral part of the coiled tubing string 14, itself.

Again, the tool 20 of the present invention is comprised of a pluralityof known elements 21, e.g. logging sensors, perforating charges, or thelike, which are fixed at known distances from each other in a relativelyflexible housing 22. Where the elements are hydrophones, the requiredcoupling to the formations to be logged will be provided by the wellfluids that are normally present in the wellbore 11 or which may beintroduced into the wellbore 11 by pumping through coiled tubing 14 orthrough tree 12. Where the elements are geophones, it may be necessaryto mount “spoolable anchors” or the like on the housing 20 to providethe acoustical coupling normally required for the operation of thegeophones. As to orienting gravity sensors, if used, see U.S. Pat. No.6,671,057 B2.

By effectively incorporating the plurality of elements into the coiledtubing, itself, long tools (e.g. 500 feet or more) can easily be runinto a pressurized well in a routine and fast operation. The pack-off ontop of the relative short lubricator (e.g. a few feet long) seals aroundthe coiled tubing in the same way as it would in any coiled tubingdeployment operation. The tool 20 (i.e. flexible housing 22 and elements21 inside housing 22, FIG. 1) are actually spooled onto and off the reel15 and the pack-off in the wellhead sees the housing 22 as merely partof a typical coiled tubing string.

1. A well tool comprising: a flexible housing adapted to be connected tothe end of a string of coiled tubing to become a part thereof, saidhousing being flexible enough to be wound onto a reel of a standardcoiled tubing system; and a plurality of elements fixed within saidhousing at known distances from each other.
 2. The well tool of claim 1wherein said housing is formed from a length of the same coiled tubingto which said housing is to be attached.
 3. The well tool of claim 1wherein said housing is formed from a the entire length of the samecoiled tubing.
 4. The well tool of claim 1 wherein said elementscomprise: perforating charges.
 5. The well tool of claim 1 wherein saidelements comprise: logging sensors.
 6. The well tool of claim 5 whereinsaid logging sensors comprise hyrdophones.
 7. The well tool of claim 5wherein said logging sensors comprise: gamma ray sensors.
 8. The welltool of claim 5 wherein said logging sensors comprise: geophones.
 9. Thewell tool of claim 5 wherein said logging sensors comprise: gravitysensors.
 10. The well tool of claim 1 wherein said flexible housing iscomprised of material selected from the group: steel, steel alloys,corrosion resistant alloy, titanium, fiberglass, or composite materialswhich are compatible with coiled tubing spooling technology.
 11. Thewell tool of claim 1 wherein said flexible housing has the same nominaldiameter as that of the coiled tubing string to which it is to beattached.
 12. The well tool of claim 1 wherein including: spacer meansfor spacing said elements at said known distances from each other withsaid flexible housing.
 13. The well tool of claim 12 where said spacermeans comprises: individual flexible members of known lengths which arerespectively coupled between two adjacent said elements.
 14. The welltool of claim 13 wherein each of said flexible members comprises: aknown length of a flexible hollow rod.
 15. The well tool of claim 1including: means for connecting said elements together for transmissionof power and signal transmission to and/or from element.
 16. The welltool of claim 14 wherein said means for connecting said sensorscomprise: individual lengths of wire passing through respective saidlengths of said hollow rod and connecting said two adjacent elementstogether.
 17. A method of assembling a well tool for use with a coiledtubing string, said method comprising: coupling at least two elementstogether which are spaced from each other at a known distance from eachother to thereby fix said elements in a fixed array; positioning saidarray in a flexible housing; and fixing said array of said elementswithin said flexible housing whereby said housing and said elementseffectively form an integral part of said coiled tubing string which canbe reeled onto and off of a coiled tubing reel.
 18. The method of claim17 wherein said at least two elements comprises: a plurality ofperforating charges wherein adjacent charges are coupled and spaced fromeach other at a known distance.
 19. The method of claim 17 wherein saidat least two elements comprises: a plurality of logging sensors whereinadjacent sensors are coupled and spaced from each other at knowndistances.
 20. The method of claim 17 wherein said array of saidelements is fixed within said housing by dimpling said flexible housingat each of said elements to thereby secure said respective element tosaid housing at that point.